Polyurethane foams are produced by the reaction of polyols with isocyanates in the presence of a blowing agent, with water traditionally used as a blowing agent. The reaction leading to polyurethane foam formation generally consists of the urethane reaction (gelling) and urea reaction (blowing), which is associated with carbon dioxide (CO2) production. Catalysts as well as other auxiliary agents, such as cross-linkers, blowing agents, chain extenders, surfactants, stabilizers, and antioxidants, are typically included in the composition with the polyol and isocyanate components. Catalysts can play a key role in ensuring desirable foam properties by controlling and balancing the gelling and blowing reactions during foam production. Catalysts can also have an effect on moldability and cure speed of the foam.
Tertiary amines and organometallic salts have been used in the art as catalysts for polyurethane foams. However, commonly used tertiary amine catalysts give rise to several problems, particularly in flexible, semi-rigid, and rigid foam applications. Freshly prepared foams using these catalysts often have the typical odor of the amines and give rise to increased fogging due to emission of volatile products.
The presence, or formation, of tertiary amine catalyst vapors in polyurethane products are detrimental to vinyl films or polycarbonate sheets exposed thereto. Specifically, the tertiary amine catalysts present in polyurethane foams have been linked to staining of the vinyl film and degradation of polycarbonate sheets. These PVC staining and polycarbonate decomposition problems are especially prevalent in environments wherein elevated temperatures exist for long periods of time, such as in automobile interiors.
The inventors of the current application have understood that many difficulties exist in producing desirable polyurethane foam products for consumer and industrial applications and that the preparation and identification of amine catalysts desirable for polyurethane foams is still a challenging area. For example, while some catalysts (e.g., see U.S. Pat. No. 4,517,313) are stated to reduce odor and vinyl staining relative to the use of standard triethylenediamine catalysts, they unfortunately provide weaker catalytic activity, and are not up to the standards of conventional catalysts. It is challenging to alter the chemical structure of the amine catalyst without adversely affecting its catalytic activity. In some cases catalysts need to be used at high levels in the polyurethane formulation to compensate for their lack of catalytic activity or mobility during the reactions.
Another issue relates to the stability of compositions, including foam-forming components. Pre-reacted components in a composition may exhibit a tendency to pre-gel or have poor storage stability. Yet another issue is that some catalysts that promote rapid gelling lead to foam processing and foam properties problems. For example, tear strength and elongation at break can be detrimentally affected due to a high level of crosslinking. Further, some catalysts, when subjected to elevated temperatures as are commonly encountered in automobile interiors, migrate within a foam.
The current application provides compounds, compositions, and methods for forming polyurethane foams based on the use of cyclic amine compounds.